Kabutops

Kabutops is a ruby library whichs aims to simplify creating website crawlers. You can define what will be crawled and how it will be saved in the short class definition.

With Kabutops you can save data easily to:

• ElasticSearch
• MongoDB
• Redis
• SQL Databases (via Sequel)

Example for every kind of database are located in the examples directory

Installation

You can install it via gem

gem install kabutops

Or you can put it in your Gemfile

gem 'kabutops', '~> 0.0.8'

Basic example

Example that will crawl information about gems that start on letter Q or X and save them to the ElasticSearch.

require 'kabutops'

class GemListCrawler < Kabutops::Crawler
  # just two letters with the smallest amount of gems
  collection ['Q', 'X'].map{ |letter|
               {
                 letter: letter,
                 url: "https://rubygems.org/gems?letter=#{letter}"
               }
             }

  cache true
  wait 2 # wait two seconds after each procession (we do not want to hurt rubygems)

  callbacks do
    after_crawl do |resource, page|
      links = page.xpath("//a[contains(@href, '/gems?letter=#{resource[:letter]}')]")
      links.each do |link|
        GemListCrawler << {
          letter: resource[:letter],
          url: "https://rubygems.org#{link['href']}",
        }
      end

      links = page.xpath("//a[contains(@href, '/gems/')]")
      links.each do |link|
        GemCrawler << {
          letter: resource[:letter],
          url: "https://rubygems.org#{link['href']}",
        }
      end
    end
  end
end

class GemCrawler < Kabutops::Crawler
  cache true
  wait 2 # wait two seconds after each procession (we do not want to hurt rubygems)

  elasticsearch do
    index :gems
    type :gem

    data do
      id :css, '.title > h2 > a'
      title :css, '.title > h2 > a'
      authors :css, '.authors > p'
      description :css, '#markup > p'

      downloads do
        total :lambda, ->(resource, page) {
          page.css('.downloads.counter > span > strong')[0].text.gsub(',', '').to_i
        }

        current_version :lambda, ->(resource, page) {
          page.css('.downloads.counter > span > strong')[1].text.gsub(',', '').to_i
        }
      end
    end

    callbacks do
      after_save do |hash|
        puts "#{hash[:title]} saved!"
      end
    end
  end
end

GemListCrawler.crawl!
GemCrawler.crawl!

Run it via sidekiq

bundle exec sidekiq -r ./rubygems_crawler.rb -c 1

Documents saved in the ElasticSearch will look like this one

{
  "id": "qiita_mail",
  "title": "qiita_mail",
  "authors": "ongaeshi",
  "description":" Write a gem description",
  "downloads": {
    "total": 2493,
    "current_version": 580
  }
}

Debugging

As we all know, crawler can't be written on the first time.

Therefore there are methods for debugging

FruitCrawler.debug_first # will take first from collection
FruitCrawler.debug_first 7 # will take first 7 resources
FruitCrawler.debug_random # will take random one
FruitCrawler.debug_random 3 # will take 3 random resources
FruitCrawler.debug_last # will take last from collection
FruitCrawler.debug_last 5 # will take last 5 resources
FruitCrawler.debug_all # guess what it will do
FruitCrawler.debug_resource { id: '123', url: '...' }

These methods will print out what would be otherwise saved to the database but for this time there is no save to the database.

Anonymity ala Tor

Anonymity can be easily achieved with Peasant gem. By following this guide you can create proxy instance that will forward requests to multiple tor instances.

Then use Peasant proxy address in your Crawler class definition

class MyCrawler < Kabutops::Crawler
  ...
  proxy 'localhost', 81818
  ...
end

License

This library is distributed under the Beerware license.